Welding is commonly used in industrial environments for the purposes of fabrication or assembly of metal components. However, welding fumes including gasses and particulate matter are typically emitted during the welding process. Gasses may include carbon monoxide, carbon dioxide, hydrogen fluoride, nitrogen oxides and ozone. Particulates are formed when the metal is heated, vaporizes and condenses into fine particles. In addition, oils and other metal working fluids as well as primer paints and plastics coating the workpiece may vaporize. Exposure to the gasses and particulate matter may result in metal fume fever as well as other adverse side effects such as irritation of the respiratory system and eyes and lead poisoning.
Local exhaust ventilation is used to remove and filter contaminated air. Various types of filters are incorporated into such ventilation systems and may be selected based on a variety of factors. One relatively important factor is the desired efficiency. The efficiency of a filter may be measured by a number of standards, including the minimum efficiency reporting value or MERV rating. However, eventually filters, regardless of their efficiency, become plugged. This leads to another factor in selecting filters, which is choosing either self-cleaning or disposable filters.
Self-cleaning cartridge filters can use dry compressed air to clean the filter. These filters may be relatively expensive. However, use of such systems with particulate that is not completely dry, including e.g., oil such as machine lubricants, can cause the filters to fail due to the inability to force release fluid laden particulate matter off the cartridge media, preventing reductions in static pressure desired in the cleaning process and maintenance of specified suction volumes. Disposable filters, with a life expectancy of a 1.5″ w.g. increase in static pressure, require frequent changes as they quickly become plugged and fail. Accordingly, there remains a need for improvements in filters, wherein filtration requirements can be met and filter life spans are balanced with cost.